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Lice

Topic Overview

What are lice?

Lice are tiny insects that live on
humans and feed on blood. When a large number of lice live and multiply on a
person, it is called an infestation.

Three different kinds of lice
live on humans:

Head lice are usually found in hair,
most often on the back of the neck and behind the ears. Head lice are common in
preschool and elementary school-age children. Adults can get them too,
especially adults who live with children.

Pubic lice, also called
crabs, are usually found in the pubic area. But they may also be found on
facial hair, on eyelashes, on eyebrows, in the armpits, on chest hair, and,
rarely, on the scalp.

Body lice live and lay eggs (nits) in
the seams of clothing. The lice are on the body only when they feed.

What causes a lice infestation?

Lice spread easily
from one person to another through close contact or through shared clothing or
personal items (such as hats or hairbrushes). A louse cannot jump or
fly.

What are the symptoms?

The most common symptom of
lice is itching. There are different symptoms, depending on which type of lice
you have.

Head lice may not cause any symptoms at
first. Itching on the scalp may start weeks or even months after lice have
started to spread. Scratching can make the skin raw. The raw skin may ooze
clear fluid or crust over, and it may get infected.

Pubic lice
cause severe itching. Their bites may cause small marks that look like bruises
on the torso, thighs, or upper arms. If pubic lice get on the eyelashes, the
edges of the eyelids may be crusted. You may see lice and their eggs at the
base of the eyelashes.

Body lice cause very bad itching, especially
at night. Itchy sores appear in the armpits and on the waist, torso, and other
areas where the seams of clothes press against the skin. The lice and eggs may
be found in the seams of the person's clothing but are typically not seen on
the skin.

Frequent scratching can cause a skin infection. In the
most severe cases of head lice, hair may fall out, and the skin may get darker
in the areas infested with lice.

How is a lice infestation diagnosed?

A doctor can
usually tell if you have lice by looking closely for live lice or eggs in your
hair. The doctor may also comb through your hair with a fine-toothed comb to help detect lice. He or she may look at the lice or eggs under a microscope.

Your doctor can also find pubic lice and body lice by
looking closely at your body or your clothing.

How is it treated?

Lice won't go away on their own. Be sure to do all you can to treat lice and to prevent the spread of lice.

The most common
treatment is an
over-the-counter or prescription cream, lotion, or
shampoo. You put it on the skin or scalp to kill the lice and eggs. In some
cases, you may need treatment a second time to make sure that all the eggs are
dead. If two or more treatments don't work, your doctor may prescribe a different medicine.

It's also important to wash clothing and
bedding in hot water to help get rid of lice.

Some people continue to have itching for 7 to 10 days after the
lice and eggs have been killed. Steroid creams or calamine lotion can relieve
the itching. If you have severe itching, you can try
antihistamine pills. But don't give antihistamines to
your child unless you've checked with the doctor first.

Cause

Lice are very
easily spread, usually through close personal contact. Lice infestation may be
caused by any of the three types of lice:

Head lice may be spread through close
personal contact, shared personal items (combs, brushes, hats, helmets,
clothing, or earphones), or shared bedding.

Pubic lice are spread
mainly through sexual contact and are very contagious. Most people become
infected after a single exposure to an infected person. The lice and eggs
may also survive long enough on personal items such as clothing or towels to be
spread to another person. A child who has pubic lice may have a history
of sexual abuse.

Body lice are most often spread by
contact with personal items, especially clothing and hats. They are
sometimes spread by direct personal contact.

Lice are spread from human to human. Pets don't get head lice and can't spread them to humans.

Symptoms

Itching, the most common symptom of all
types of
lice infestation, is caused by an
allergic reaction. Lice bite the skin to feed on a
person's blood. The saliva from these bites causes the allergic reaction and
itching.

Itching may not occur right away, depending on a
person's sensitivity and history of lice infestation. The first time a person
is infested with lice, it may take several weeks or months for itching to
start or to be noticed. In a repeat case of lice, a person may begin to itch
within 2 days of infestation because the
immune system reacts more quickly when exposure has
occurred before.

Some people become very sensitive to lice
bites and have unbearable itching. Others build up tolerance to the bites and
have little or no itching, even with repeated infestations.

In
addition to itching, symptoms of lice infestation vary depending on which type
of lice is present.

Head lice

Head lice and their eggs (nits) can be
seen on hair, the nape of the neck, and behind the ears. They can vary in color
from white to brown to dark gray. The eggs are tiny round or oval shapes that
are tightly attached to the hair near the scalp and do not slide up and down on
the hair.

Frequent scratching may cause broken skin or sores to
form on the scalp. The damaged skin may weep clear fluid or crust over, and it
may become infected. In response to infection, the
lymph nodes behind the ears and in the neck may become tender and
swollen.

Pubic lice

A
pubic lice infestation may cause itching around the genitals as well as the
anus, armpits, eyelashes, and other body areas with hair. Pubic lice bites may
cause small, flat, blue-gray marks (maculae cerulea) that look like bruises on the torso,
thighs, or upper arms. The marks may last for several months, even after all
lice have been killed. Pubic lice, like head lice, can be seen on shafts of
hair.

Pubic lice that infest the eyelashes and eyelids may cause
irritation and crusting in those areas. The lice may be visible near the base
of eyelashes.

Pubic lice tends to be spread by sexual contact. If you or your teen has pubic lice, you may also have some other sexually
transmitted infection (STI). Symptoms of STIs can include itching, tingling,
burning, or pain of the genitals. For more information about STIs, see the
topic
Sexually Transmitted Infections.

Body lice

Itchy sores from
body lice usually develop in the armpits, around the waist, and along the
trunk where seams of clothes press against the skin. The lice and eggs are
generally not seen on the skin but may be found in the seams of the person's
clothing.

Other conditions, such as dandruff or
scabies, can cause symptoms similar to those of a lice
infestation.

What Happens

Lice will not go away without treatment. If the initial treatment does not kill all of
the eggs (nits), a follow-up treatment may be required 7 to 10 days later to
kill the newly hatched
lice. Itching may last for 7 to 10 days even after
successful treatment.

After treatment, dead eggs may remain in the
person's hair until they are removed. Some schools have a policy of not
allowing children to return to school until they are free of eggs.

If your child has lice, report it to your child's day care provider or
school so that other children can be checked.

Some children and parents think about or feel lice crawling even after the lice problem is gone. If you or your child feels like symptoms are lasting or feels troubled after the lice problem is gone, talk to your doctor.

Complications

Frequent scratching can cause mild
complications such as skin infections. In severe cases, hair may fall out. Some
people may develop thickened, darkened skin in areas that are infested with
lice over a long period.

What Increases Your Risk

Things that increase the
risk of getting
lice include:

Attending school or day care. Young children in
school or day care often play together closely and share hats, brushes, and
other items. This behavior puts them at a higher risk for getting and
transmitting
head lice.

Living in crowded or unclean conditions. People who
live in crowded conditions and who do not or cannot bathe and wash their
clothing regularly (such as people who are homeless, victims of war or natural
disasters, or refugees) are at increased risk for
body lice.

When To Call a Doctor

If you suspect
lice infestation (pediculosis), you can try an
over-the-counter lice medicine or visit your doctor to
double-check your symptoms. Call a doctor if:

You have severe nighttime itching that does not
go away after a few days.

You see live lice or new eggs (nits)
after using the medicine (prescription or nonprescription).

You
have serious side effects after using a product to treat
lice.

You have signs of a skin infection. These may include:

Increased pain, swelling, heat, redness, or
tenderness.

Red streaks extending from the affected
area.

Discharge of pus.

Fever of
100°F (37.8°C) or higher with
no other obvious cause.

Watchful waiting

Lice will not go away without proper treatment.
Even if they don't bother you much, lice can be spread to other household
members, sex partners, or other people you have close personal contact
with. If you think you have lice, try an over-the-counter lice medicine or call a
doctor.

Who to see

If you need help
treating a lice problem, contact any of the following:

Exams and Tests

To find out if your child has lice, the doctor will do a close
visual exam to look for live
lice or their eggs (nits) on the hair. The doctor may
also use a fine-toothed comb to help detect lice. He or she may need to look at the lice or eggs under a microscope to confirm the diagnosis.

Treatment Overview

Lice will not
go away without proper treatment. Treatment should begin as soon as symptoms of
lice are noticed or when live lice and eggs (nits) are seen on the person's
body or in clothing. Specific treatment depends on the type of lice
infestation.

Head lice and
pubic lice are killed with
over-the-counter or prescription medicines applied to
the skin or scalp, and sometimes with a prescription pill. The
most common way to treat lice is to use medicated creams, lotions, or shampoos
that kill lice.

Body lice, which live and lay eggs in the seams of
clothing, are destroyed by washing clothing in hot water [130°F (54.4°C) or higher] for 5 minutes or
more. This will usually kill adult lice and prevent eggs from hatching. Body
lice are only present on the skin when they feed and will usually go away if you bathe daily and wear clean clothes.

Children with head lice can return to school or
day care after their first treatment. Some schools have a "no nits" policy in which the child can go back to school or day care only after eggs have
been removed. "No nits" policies are discouraged by medical experts. Most doctors agree that a child should be allowed to return
to class after proper treatment and should be urged to avoid close head-to-head
contact with other students. Confidentiality should be maintained so as not to
embarrass a child who has head lice.

Itching may continue even
after all lice are destroyed. This happens because of a lingering
allergic reaction to their bites. Over-the-counter
cortisone (corticosteroid) creams or calamine lotion may help.
For severe itching,
antihistamine medicines (such as Benadryl) or
stronger, prescription-strength corticosteroid creams may be needed. Don't give
antihistamines to your child unless you've checked with the doctor first. And
don't use cortisone cream for longer than 7 days without talking with your
doctor. Do not use the cream on children younger than age 2 unless your doctor
tells you to. And don't use it in the rectal or vaginal area in children
younger than age 12 unless you've checked with the doctor first.

What to think about

Who should be treated?

Household members and anyone who has been
in close contact with a lice-infested person should be checked for signs of
lice. If they have itching and skin sores that are commonly seen with lice
infestations or if lice or eggs are found on their bodies, treatment is
recommended.

Anyone who has shared a bed with a person who has lice
should be treated, whether they have symptoms or not.

If you still see live lice on a household member 7 to 10 days after he or she had the first treatment, it's best for that person to have a second treatment. Sometimes the first treatment doesn't work.

People who have pubic lice are encouraged to tell their sex partners so that they can also be
treated. It is also a good idea to see a doctor to be tested for
other
sexually transmitted infections.

Treatment is not likely to work if:

You don't use the medicine as directed.

You stay in contact with other people who have lice but who did not get treated.

Lice become resistant to the medicines and don't die. This occurs in some locations more than others. Talk to your doctor if you think a lice medicine isn't working as expected.

Prevention

Head lice are easily spread among children because kids commonly share hats, combs, and other items. If you or your child has head lice, you can help prevent others from getting it if you avoid head-to-head (hair-to-hair) contact during activities inside the home and outside the home.
Also, don't share clothing, bedding, hair brushes and accessories, pillows, stuffed animals, or towels. Frequently examining the scalps of your school-age children may help you
discover and treat lice before they spread to the rest of your family. Avoiding
prolonged close contact with a person who has lice will also reduce your
risk.

Pubic lice are spread primarily among people who have
many sex partners. Reducing the number of sex partners you have may help reduce
your risk of getting pubic lice.

Body lice may be
prevented by bathing regularly and changing clothes daily. Body lice live on
clothing, not on the body. Washing clothing in hot water [130°F (54.44°C) or higher] will usually kill
adult lice and prevent eggs from hatching. Body lice that are on the skin
usually go away on their own with daily bathing and wearing clothes that are
not contaminated. Medicines to kill body lice are usually not needed.

Medications

There are both
over-the-counter medicines and prescription products
to treat head
lice and pubic lice. Most products come as a shampoo, creme rinse, or
lotion (topical treatment) that is applied to the affected areas, left on for a
period of time, and then rinsed off. Doctors sometimes prescribe a pill to treat lice when two or more approved topical medicines have not
worked.

If lice infest the eyelashes, your doctor may prescribe an eye ointment for you.

Because body lice live in clothing, not on the body, medicines are generally not needed unless the person is severely
infested. The most common way to kill body lice and eggs is to wash clothing
and bedding in hot water [130°F (54.5°C) or higher] in a washing machine.

Medicine choices

Over-the-counter (OTC) medicines that are recommended for head or pubic lice include:footnote 1

Permethrin creme rinse 1% (such as Nix), which is a common first choice for treating head lice. It
kills lice and their eggs for 2 weeks or more after it has been rinsed
off.

Shampoos containing pyrethrins and piperonyl butoxide
(such as Rid), which are left on the hair for 10 minutes and then rinsed out. A
second treatment is needed 9 days after the first to kill newly hatched
lice.

There are other OTC products for lice, but not all of them have good evidence that their benefits outweigh the side effects and other risks. Check the product label. Be sure to follow the directions about proper use and safety. And talk to your doctor or pharmacist about whether these products are safe for young children.

Prescription medicines that are recommended for head or pubic lice include:footnote 1

Benzyl alcohol 5% (Ulesfia), which is used to treat head lice. It is applied to the hair on the head, left on for 10 minutes, and then rinsed off.

Malathion lotion (Ovide), which is used to treat head lice. It is applied to hair on the head, left on for 8 to 12 hours, then
rinsed off. If lice are still present 7 to 9 days later, a second treatment
must be done.

If these OTC or prescription medicines aren't working, your doctor may prescribe a different medicine to help get rid of lice. These include ivermectin (Sklice or Stromectol), permethrin 5% (Elimite), and spinosad (Natroba). In rare cases, lindane may be prescribed. But lindane is falling out of favor because of the potential for serious nervous system side effects. The American Academy of Pediatrics no longer recommends lindane as a treatment for head lice.

Antihistamines (both prescription and nonprescription)
can help relieve the itching that often occurs with lice. These medicines may cause
drowsiness. Don't give antihistamines to your child unless you've checked with
the doctor first.

If there is a serious skin infection,
antibiotics may be needed.

What to think about

It is not necessary to remove
lice eggs from hair after treatment with topical medicines, but some people
may wish to remove them for cosmetic reasons.

Most products used
to treat lice may cause side effects if they are not used properly. Never use a
product more than two times (with less than 7 days between uses) without first
consulting a doctor.

There is some concern that lice are becoming
resistant to (can no longer be killed by) permethrin or other medicine used to
treat lice infestations. It is also possible that lice may persist after
treatment because the medicine was not used properly or because the person was
reinfected by someone else who was still infected with lice.

Other Treatment

Some people try other treatments (such as using petroleum jelly or olive oil to smother lice). But there is not strong evidence that other treatments such as these work well or are safe to treat lice.

Head-shaving helps get rid of
head
lice. But this method can cause distress to the person whose head is shaved. After cutting or shaving the hair, put the hair
into a garbage bag right away and seal it so that lice cannot spread to other
areas in your home.

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